A known dewatering machine of this type comprises inner and outer sleeves disposed coaxial with each other, and a coil-like screw disposed in an annular space chamber defined between said inner and outer sleeves, said screw being rotatably supported at one end thereof by said inner and/outer sleeves.
And a material to be dewatered is charged into said annular space chamber through a charge port disposed in one end of the outer sleeve and is compressed for dewatering by the rotation of said coil-like screw. The dewatered material is discharged through a discharge port formed in the end of the annular space chamber corresponding to the other end of said outer sleeve.
In this connection, according to the above arrangement, one end of the coil-like screw is only supported by the inner and/or outer sleeve, the other end not being supported by a special mechanism.
For this reason, the other end of the coil-like screw is elastically deformed under the reaction during compression, that is, the coil-like screw is contracted toward one end; therefore, there is a drawback that compression of material to be dewatered cannot be fully effected.
In addition, increasing the thickness of the coil-like screw would be effective to prevent elastic deformation but this is disadvantageous in that it leads to an increase in weight and to a need for increasing the strength of the dewatering machine, resulting in a large-sized apparatus with an increase in cost.